1. Field of the Invention
The present invention relates to a reproducing apparatus and a reproducing method, in which moving picture data read out from a recording medium is once accumulated into a buffer memory and when an amount of accumulated data is less than a predetermined amount, a processing speed of an image compression decoder is reduced, thereby allowing images to be slowly reproduced and preventing interruption of the images.
2. Description of the Related Art
In recent years, a digital camera for digitizing still pictures photographed by a video camera and recording it into a recording medium such as semiconductor memory, magnetic disc, optical disc, or the like has been being rapidly spread. When the digital camera is used, the photographed pictures can be reproduced on the spot and the digital still pictures can be easily transmitted to a personal computer and can be easily edited and proceeded.
Further, in the digital camera as described above, a digital camera which can record not only the still pictures but also moving pictures has already been developed. In the digital camera which can record the moving picture, a video signal of a moving picture taken by a video camera is digitized and is compressed by the MPEG (Moving Picture Experts Group) system or the MPEG2 system. The compressed digital video signal is recorded onto a recording medium such as semiconductor memory, magnetic disc, optical disc, or the like.
In the digital video camera which can record the moving picture as mentioned above, since an amount of data to be recorded becomes enormous, a recording medium having a large capacity is demanded. Since the digital camera is often carried to the outside and is used, it is desirable that the digital camera is small and is easy to handle.
The applicant of the present invention proposes to use an MD (Mini Disc, trademark) which improves a recording capacity and a data rate by improving physical characteristics and signal processes.
As is well-known, the MD is an optical disc or a magnetooptic disc having the diameter of 64 mm enclosed in a cartridge. According to the conventional MD format called MD-DATA1, a recording capacity is equal to 140 MB when data is recorded and a data rate is equal to 133 kB/sec. It cannot be said that the conventional MD is sufficient for recording the moving picture data.
A new MD format is called MD-DATA2, a recording capacity is equal to 650 MB, and a data rate is equal to 589 kB/sec. As mentioned above, in the new MD format, as compared with the conventional format, the recording capacity is larger and the data rate is higher by more than four times and it is sufficient for recording even moving picture data. Since the MD is either an optical. disc or magnetooptic disc, an accessing speed is high. The MD has been already widely spread as a music recording disc and is very reliable. The MD is, therefore, suitable to record the moving picture data in the digital video camera.
An MD recording and reproducing apparatus has a buffer memory called a shock-proof memory. Data reproduced. from a disc is once stored in the buffer memory and is outputted to the outside. By the buffer memory, even when a disturbance to a certain extent occurs, the reproduction is not interrupted. Even in a digital video camera using the MD as a recording medium, reproduction data from a disc is once stored into the buffer memory and is sent to a decoder for image decompression.
That is, moving picture data has been compressed and recorded in the disc. At the time of reproduction, reproduction data from the disc is transmitted to the decoder for image decompression and is decompressed. By a difference between a transfer rate of the data which is reproduced from the disc and a transfer rate of the data which is sent to the decoder for image decompression, a certain amount of data is always stored in the buffer memory. As mentioned above, since a predetermined amount of data is always stored in the buffer memory, even if a disturbance to a certain extent occurs, the moving pictures can be reproduced continuously.
Even if the buffer memory as mentioned above is provided, when a disturbance is large and an abnormal rotation of the disc, an out-of focusing state, an out-of tracking state, or the like occurs, the data in the buffer memory is exhausted. When the data in the buffer memory is exhausted as mentioned above, the moving picture cannot be reproduced and the reproduction is temporarily interrupted.
It is, therefore, an object of the invention to provide a reproducing apparatus which prevents the reproduction from being temporarily interrupted even when a disturbance is large.
In view of the problems, it is an object of the invention to provide a reproducing apparatus comprising: data reading means for reading out moving picture data from a recording medium in which the moving picture data has been recorded; data storage means for storing the moving picture data read out by the data reading means at a predetermined transfer rate; data processing means for processing the moving picture data read out from the data storage means at a variable processing speed; and control means for monitoring an amount of data stored in the data storage means and, when the data amount is less than a predetermined value, decreasing the processing speed of the data processing means.
The above reproducing apparatus further has image display means for displaying the moving picture data from the data processing means, wherein when the data amount in the data storage means is less than the predetermined value, the moving picture data in the image displaying means is displayed at a low speed.
It is another object of the invention to provide a reproducing method comprising the steps of: reading out moving picture data from a recording medium in which the moving picture data has been recorded; storing the read-out moving picture data into a memory at a predetermined transfer rate; monitoring an amount of data in the memory; and processing the data read out from the memory at a low speed when it is determined in the monitoring step that the data amount is less than a predetermined value.
The above reproducing method further comprises the step of displaying the moving picture data processed in the data processing step.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.